- Voyager 1, one of the earliest space probes and the most distant human-made object from Earth, continues to operate and send valuable data back to Earth, even after four decades in space.
- Traveling at an astounding speed of 11 miles per second, Voyager 1 has been steadily moving away from Earth, now venturing over 3.5 Astronomical Units (AU) farther from the Sun each year.
- The probe has crossed the heliopause, marking its entry into interstellar space. The heliopause is the boundary where the solar wind weakens, allowing the interstellar medium to dominate—an event Voyager 1 experienced in 2012.
- Despite being surrounded by sparse interstellar medium, Voyager 1 occasionally encounters disturbances, such as magnetic spikes and pressure fronts, providing valuable insights into the outer reaches of our solar system.
- Voyager 1 is anticipated to enter the Oort cloud in approximately 300 years, though its diminishing fuel supply, powered by Plutonium-238, poses a significant challenge, potentially limiting its operational capabilities by the mid-2020s.
Voyager 1, a venerable space probe and the farthest human-made object from Earth, is still conducting scientific operations in the depths of space.
Having embarked on its mission over four decades ago, Voyager 1 last approached a planet when it flew past Saturn in 1980. Yet, despite its ever-increasing distance from a fading sun, the probe continues to relay crucial information to Earth, as recently affirmed by scientists in The Astrophysical Journal.
Voyager 1’s extraordinary journey sees it hurtling through space at an astonishing rate of 11 miles (17 kilometers) per second. Each passing year, it ventures an additional 3.5 Astronomical Units (AU) away from Earth, steadily advancing towards the outer bounds of our solar system.
Defining the “edge of the solar system” encompasses various perspectives, with one focusing on the heliopause—a boundary region where the solar wind weakens, unable to resist the interstellar medium, composed of plasma, dust, and radiation, which pervades most of space.
When Voyager 1 departed Earth in 1977, scientists were uncertain of the heliopause’s location. Some believed it might be as close as 10 or 5 AU, aligning with the orbits of Jupiter and Saturn, respectively. In reality, the heliopause lies approximately 120 AU distant. This revelation came to light over three decades after the probe’s departure, as Voyager 1 breached this boundary in August 2012, firmly establishing its presence in interstellar space.
In this realm, the interstellar medium prevails, though it is notably sparse. A volume of Earth’s sea-level atmosphere contains over a trillion times more molecules than an equivalent volume of even the densest parts of the interstellar medium. Voyager 1 navigates through an even more tenuous region, characterized by a prevailing calmness.
Yet, at intermittent intervals, Voyager 1 encounters phenomena of interest. Notable instances include magnetic spikes accompanied by bursts of energetic electrons, generating oscillating electric fields. These phenomena, experienced in 2012 and 2014, constitute the farthest-reaching effects of the sun, extending beyond the heliopause.
In 2020, Voyager 1 encountered another surge in magnetic field strength, though without the intense electrical oscillations. This is believed to be a pressure front—a subtler disturbance extending into the interstellar medium. A similar encounter occurred in 2017, showcasing the complexity of the environment Voyager 1 navigates.
Astrophysicist Jon Richardson from MIT emphasizes that this recent discovery underscores Voyager 1’s capacity to surprise scientists. Typically, a shock in the surrounding plasma is required to measure its density, but observations like this enable continual monitoring, even at a staggering distance of over 13 billion miles from Earth.
Furthermore, Voyager 1 remains under the gravitational influence of the sun. It is projected that in around 300 years, the probe will approach the inner edge of the Oort cloud—a vast collection of comets extending several light-years away.
While the Oort cloud remains elusive, Voyager 1’s dwindling fuel supply poses a significant challenge. The probe relies on Plutonium-238, with an 88-year half-life, to power its generator. Consequently, scientists face decisions about which components to maintain functionality. By the mid-2020s, the probe may no longer have the capacity to power even a single instrument.
Nonetheless, scientists like Bill Kurth remain hopeful, aspiring to prolong the probe’s mission until 2027—a milestone that surpasses the expectations of Voyager 1’s original designers.